6/1/2014-6/1/2037, and Government National Mortgage Assn. 5.000%-8.000%,

9/20/2030-11/20/2035)

5.240%

6/8/2007

1,000,000

1,000,000

Deutsche Bank Securities, Inc.

(Dated 5/31/2007, Repurchase Value $145,021,000,

collateralized by Federal Home Loan Bank 5.000%-5.375%,

9/18/2009-6/10/2016, Federal Home Loan Bank Discount Note, 7/11/2007,

and, Federal Home Loan Mortgage Corp. 6.875%, 9/15/2010)

5.300%

6/1/2007

145,000

145,000

Goldman, Sachs&Co.

(Dated 5/31/2007, Repurchase Value $2,821,000,

collateralized by Federal Home Loan Bank Discount Note, 8/10/2007,

and Federal National Mortgage Assn. 4.625%, 10/15/2013)

5.300%

6/1/2007

2,821

2,821

Greenwich Capital Markets, Inc.

(Dated 5/10/2007, Repurchase Value $502,406,000,

collateralized by Federal National Mortgage Assn.

5.000%-7.500%, 5/1/2018-6/1/2047)

5.250%

6/12/2007

500,000

500,000

Morgan Stanley&Co., Inc.

(Dated 5/8/2007, Repurchase Value $1,004,367,000,

collateralized by Federal Home Loan Mortgage Corp. 5.500%,

4/1/2037-6/1/2037, and Federal National Mortgage Assn.

5.000%-6.000%, 4/1/2035-2/1/2037)

5.240%

6/7/2007

1,000,000

1,000,000

UBS Securities LLC

(Dated 5/31/2007, Repurchase Value $88,013,000,

collateralized by Federal Home Loan Mortgage Corp.

3.500%-3.625%, 9/15/2007-9/15/2008)

5.300%

6/1/2007

88,000

88,000

UBS Securities LLC

(Dated 5/7/2007, Repurchase Value $1,004,375,000,

collateralized by Federal Home Loan Mortgage Corp.

3.500%-16.250%, 6/1/2007-5/1/2047, and

Federal National Mortgage Assn. 4.500%-7.000%,

3/1/2015-11/1/2036)

5.250%

6/6/2007

1,000,000

1,000,000

Total Repurchase Agreements

(Cost $5,835,006)

5,835,006

Total Investments (103.5%)

(Cost $91,402,833)

91,402,833

Other Assets and Liabilities - Net (-3.5%)

(3,082,859)

Net Assets (100%)

88,319,974

1

Represents
annualized yield at date of purchase for discount securities, and coupon for
coupon-bearing securities.

2

The
issuer operates under a congressional charter; its securities are neither issued nor
guaranteed by the U.S. government. If needed, access to additional funding from the
U.S. Treasury (beyond the issuer's line of credit) would require congressional action.

3

Adjustable-rate
note.

4

Security
exempt from registration under Section 4(2) of the Securities Act of 1933. Such
securities may be sold in transactions exempt from registration only to dealers in
that program or other "accredited investors." At May 31, 2007, the aggregate value of
these securities was $8,647,613,000, representing 9.8% of net assets.

The
issuer operates under a congressional charter; its securities are neither issued nor
guaranteed by the U.S. government. If needed, access to additional funding from the
U.S. Treasury (beyond the issuer's line of credit) would require congressional action.

Disclosure Controls and Procedures. The Principal Executive and Financial
Officers concluded that the Registrants Disclosure Controls and Procedures
are effective based on their evaluation of the Disclosure Controls and
Procedures as of a date within 90 days of the filing date of this report.

(b)

Internal Control Over Financial Reporting. During the last fiscal quarter, there
was no significant change in the Registrants internal control over
financial reporting that has materially affected, or is reasonably likely to
materially affect, the registrants internal control over financial
reporting.

Item 3:

Exhibits.(a) Certifications.

Pursuant to the requirements of the
Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has
duly caused this report to be signed on its behalf by the undersigned, thereunto duly
authorized.

VANGUARD MONEY MARKET RESERVES

BY:

(signature)
(HEIDI STAM)JOHN J. BRENNAN*CHIEF EXECUTIVE OFFICER

Date:

July 20, 2007

Pursuant to the requirements of the
Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has
been signed below by the following persons on behalf of the registrant and in the
capacities and on the dates indicated.

VANGUARD MONEY MARKET RESERVES

BY:

(signature)
(HEIDI STAM)JOHN J. BRENNAN*CHIEF EXECUTIVE OFFICER

Date:

July 20, 2007

VANGUARD MONEY MARKET RESERVES

BY:

(signature)
(HEIDI STAM)THOMAS J. HIGGINS*TREASURER

Date:

July 20, 2007

* By Power of Attorney. See File Number 002-65955-99, filed on July 27, 2006. Incorporated by Reference.